Japanese Patent Application Laid-Open Publication No. 2010-86112 discloses an automotive navigation system that includes an information providing device that synthesizes a low frequency sound signal and a high frequency data signal by use of a synthesizer, to output from a speaker sound derived from the synthesized signals; and a guide terminal that, based on the sound received by a microphone, reproduces the sound signal and the data signal.
In a conventional automotive navigation system, a high frequency signal and a low frequency signal are uni-directionally transmitted from an information processing device to a guide terminal, by synthesizing signals of different bands, and a sound is then output that corresponds to the synthesized signals. However, a drawback exists in the art in that it is not possible to transmit, for example, a high frequency signal in one direction and a low frequency signal in another opposing direction.